Interleukin-12 (IL-12) is a heterodimeric cytokine (p70) composed of two subunits (p35 and p40), and plays key roles in immune responses by bridging innate resistance and antigen-specific adaptive immunity. Trinchieri (1993) Immunol Today 14: 335. For example, it promotes type 1 T helper cell (Th1) responses and, hence, cell-mediated immunity. Chan et al. (1991) J Exp Med 173: 869; Seder et al. (1993) Proc Natl Acad Sci USA 90: 10188; Manetti et al. (1993) J Exp Med 177: 1199; and Hsieh et al. (1993) Science 260: 547.
Over-production of IL-12 causes excessive Th1 responses, and may result in inflammatory diseases and immune disorders, such as insulin-dependent diabetes mellitus, multiple sclerosis, rheumatoid arthritis, psoriasis, Crohn's disease, or sepsis. See, for example, Gately et al. (1998) Annu Rev Immunol. 16: 495; and Abbas et al. (1996) Nature 383: 787. Thus, inhibiting IL-12 production is an approach to treat the just-mentioned diseases. Trembleau et al. (1995) Immunol. Today 16: 383; and Adorini et al. (1997) Chem. Immunol. 68: 175. For example, production of IL-12 and the resultant excessive Th1 type responses can be suppressed by modulating IL-12 production. A compound that down-regulates IL-12 production can be used for treating or preventing inflammatory diseases. Ma et al. (1998) Eur Cytokine Netw 9: 54. In addition, IL-12 has been implicated in promoting various immune diseases (see for example, Segal et al. (1998) J. Exp. Med. 187:4, 537-546 and Williamson et al., J. Immunol. (1997) 159: 15, 1208-1215). Accordingly, a compound that inhibits IL-12 production can be used for treating or preventing immune diseases.
IL-12 also plays a role in bone loss diseases, particularly those involving osteoclasts. Osteoclasts are unique multinucleated cells within bone that are responsible for bone degradation and resorption. These are the only cells in the body known to be capable of this function. Osteoclasts have a high capacity for the synthesis and storage of enzymes, including acid hydrolases and carbonic anhydrase isoenzyme II. Osteoclasts share phenotypic characteristics with circulating monocytes and tissue macrophages (N. Kurihara et al., Endocrinology 126: 2733-41 (1990); G. Hattersley et al, Endocrinology 128: 259-62 (1991)). These cells are derived from mononuclear precursors that are the progeny of stem-cell populations located in the bone marrow, spleen, and liver. Proliferation of these stem-cell populations produces osteoclastic precursors, which migrate via vascular routes to skeletal sites. These cells then differentiate and fuse with each other to form osteoclasts, or alternatively, fuse with existing osteoclasts.
The regulation of osteoclastic formation and activity is only partly understood but it is known that excessive bone resorption by osteoclasts contributes to the pathology of many human diseases associated with excessive bone loss, including periodontal disease, non-malignant bone disorders (such as osteoporosis, Paget's disease of bone, osteogenesis imperfecta, fibrous dysplasia, and primary hyperparathyroidism) estrogen deficiency, inflammatory bone loss, bone malignancy, arthritis, osteopetrosis, and certain cancer-related disorders (such as hypercalcemia of malignancy (HCM), osteolytic bone lesions of multiple myeloma and osteolytic bone metastases of breast cancer and other metastatic cancers).
There is a continuing unmet need for new therapeutics to treat the aforementioned conditions. Trisubstituted pyrimidine compounds disclosed, for example, in U.S. Pat. No. 6,693,097, filed on Nov. 30, 2001, U.S. Pat. No. 6,660,733, filed on Jul. 10, 2002, U.S. patent application Ser. No. 10/305,039, filed on Nov. 26, 2002, U.S. application Ser. No. 10/656,671, filed on Sep. 5, 2003, U.S. application Ser. No. 10/655,672, filed on Sep. 5, 2003 and U.S. Provisional Application No. 60/585,124, filed on Jul. 1, 2004, the entire teachings of the aforementioned patents and patent applications are incorporated herein by reference, have demonstrated efficacy in inhibiting the production of IL-12 and, thus, are useful in treating inflammatory diseases and autoimmune diseases. Disclosed syntheses of trisubstituted pyrimidine compounds produce a mixture of regioisomers wasting a portion of the starting materials in the production of undesirable isomers, and sacrificing some of the desired isomeric product in the separation of the undesirable isomers from the desired product. Therefore, a need exists for improved (e.g., more efficient, less costly, safer, more convenient, higher yielding, higher purity, etc.) methods to produce trisubstituted pyrimidine compounds (and compositions thereof) useful for inhibiting the production of IL-12 and in treating diseases or disorders related to the over production of IL-12.